soc: imx8m: Dump higher 64bits UID

i.MX8MP UID is actually 128bits and partitioned into two parts.
The 1st 64bits are at 0x410 and 0x420, and 2nd 64bits are at 0xE00
and 0xE10.

Dump the whole 128bits for i.MX8MP, by set soc_uid as an array with two
u64.

Signed-off-by: Peng Fan <peng.fan@nxp.com>
Reviewed-by: Marco Felsch <m.felsch@pengutronix.de>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>